In many food preparation facilities, such as commercial kitchens and restaurants, the sink is a major tool used for disposing of various types of food waste. In some cases liquid food wastes, such as FOG are poured down the sink, and in other cases a mechanical chopper such as a garborator is used to shred the food waste as it leaves the sink and enters the wastewater system. Many food preparation establishments, such as commercial restaurants and the like, have multiple sinks for such food waste disposal.
In many jurisdictions, the disposal from commercial kitchens of FOG and FOG laden debris into the sanitary sewage system is prohibited. There are a number of reasons why this is so, including the ability of those types of materials to clog or plug sanitary sewage systems and the difficulty of adequately treating such materials in a sewage treatment facility. Therefore, many jurisdictions require that these materials be removed from the wastewater stream before permitting the wastewater stream to be added to the sanitary sewer system.
As a result, devices known as grease interceptors have been developed. These grease interceptors are connected to the wastewater effluent stream from the food preparation kitchen or other facility and are located before the sanitary sewer, typically within the kitchen. The grease interceptors may take a number of forms, but typically consist of an in-line container which is mounted at or below grade within the wastewater discharge system downstream of all of the sinks and the like. The container includes features that are configured to allow fats, oils and grease to float to the surface of the container where they can be skimmed off and physically removed for controlled disposal. In this way these wastes are removed from the wastewater before the wastewater enters the sanitary sewer system. Some examples of prior art grease interceptors include the following:
U.S. Pat. No. 4,400,274
U.S. Pat. No. 4,940,539
U.S. Pat. No. 5,360,555
U.S. Pat. No. 5,431,826
U.S. Pat. No. 5,827,425
U.S. Pat. No. 5,993,646
U.S. Pat. No. 6,517,715
U.S. Pat. No. 6,800,195
U.S. Pat. No. 7,011,752
U.S. Pat. No. 7,300,588
U.S. Pat. No. 7,452,472
U.S. Pat. No. 7,596,845
U.S. Pat. No. 7,641,805
U.S. Pat. No. 7,682,509
U.S. Pat. No. 8,007,016
Canadian Patent No. 2,299,134
Canadian Patent No. 2,562,825
Canadian Patent No. 2,672,865
While these different inventions all have various features and benefits, a consistent problem that grease interceptors have to deal with is non-floating solid materials that may be also washed down the sink drain and into the grease interceptor. These materials are organic or inorganic and they can become trapped in the layer of fats, oils and grease accumulated at the surface of the grease interceptor or settle out by gravity and then decompose anaerobically. This decomposition of solids creates very foul odours and noxious gases which makes emptying the FOG from the grease interceptor container highly undesirable and a very unpleasant job. Therefore, efforts have been made in the prior art to eliminate the ability of solids to enter into the separation chamber of the grease interceptor. However, these prior art devices are often complicated, cumbersome, expensive to implement and may be difficult to clean due to permanently installed baffles. Further, different types of commercial kitchen establishments have different types of waste. Some produce solids that are large, some produce fine solids, and some are solids free. What is desired is an easy to use and effective way of removing solids from the wastewater stream before they can enter and decompose or otherwise plug the grease interceptor or downstream drains. What is also desired is a way to adapt the solid separation capabilities of the grease interceptor to suit the waste produced by a specific kitchen or restaurant.